L’AFFLEUREMENT OPHIOLITIQUE DU GROUPE DE VOLTRI (LIGURIE, ITALIE): HÉTÉROGÉNÉITÉ DES SOLS ET DIVERSITÉ FLORISTIQUE. THE OPHIOLITIC OUTCROP OF VOLTRI GROUP (LIGURIA, ITALIA): SOIL AND FLORA DIVERSITY

Abstract

The authors carried out quantitative ecological investigations in Gruppo di Voltri (Liguria, Italy) in order to compare vascular flora, vegetation and soil in two different types of outcrops - serpentinites and calc-schists - in close contact with each other. In particular, the authors analyzed: richness and species diversity, floristic peculiarities, the indicator values of floristic cortege and physical and chemical characters of soils. The results of the analysis allow us to highlight in the serpentines: extreme poverty in nutrients, low Ca/Mg ratio and high concentrations of available Ni. The serpentine syndrome on the plant component is expressed above all in relation to these characteristics of the soils rather than a concentration not exceptionally high of available Mg. The phyto-ecological analysis by Ellenberg’indices has highlighted bioindicator values relatively more effective for the floristic cortege of serpentinites especially in relation to the poor availability of nutrients. The principal components analysis (PCA) of correlations soils-flora showed significant differences between the two substrates despite the mosaic configuration and almost mingling of soils.